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Cast it in metal: weight, cost and castability

Drop an STL, or a model from an AI 3D tool, and see it in silver, bronze or gold: what it weighs, what the metal costs and whether it will cast. Free, with no account, and the file never leaves your computer.

A free page from Jart that measures a 3D model in your browser: the metal volume from the model's own triangles, its weight in sterling silver, bronze or 9k, 14k or 18k gold, the metal cost at a price per gram you can change (a dated default, never a live price), and the cast check: closed metal, wall thickness with a heat map, prongs and stone seats. The caster pack ZIP is made on your computer too. Nothing is uploaded and no account is needed.

Drop your STL here

Or a GLB, OBJ, 3MF or 3DM file, from CAD or an AI 3D tool. It is measured on this computer and never uploaded.

How to check a model for casting

  1. Drop the model. Drop an STL, OBJ, GLB, 3MF or 3DM file on the box, or choose it. It is read in your browser.
  2. Check the size. The page reads the file's unit. If the piece is the wrong size, as models from AI tools often are, type its real largest side in millimetres.
  3. Choose the metal. Pick silver, bronze or 9k, 14k or 18k gold. The weight and the metal cost follow; type your own price per gram.
  4. Read the cast check. Closed metal and wall thickness, and prongs and stone seats when the model has stones. Turn on Wall thickness to see the thin areas in red.
  5. Send it to your caster. Download the caster pack: the metal as an STL, your file, the facts, the cast check and a README with each file's SHA-256.

How much does it cost to cast a ring in silver?

A plain band 17.3 mm inside (about US size 7), 4 mm wide and 1.8 mm thick holds 432 mm³ of metal. In sterling silver that is 4.49 g, about US$6.87 of metal at the default price; in bronze 3.80 g (US$0.15); in 14k gold 5.66 g (US$434); in 18k gold 6.70 g (US$658).

The casting house then adds its own costs: a casting fee per piece or per flask, the metal in the sprue (often credited back), casting loss, finishing and polishing, and setting any stones. Those depend on the caster, so this page prices the metal only. Ask your caster for theirs, and type their price per gram if they sell the metal.

How is the weight worked out?

The page adds up the volume enclosed by the model's own triangles, which is exact for a closed mesh, and multiplies it by the metal's density: bronze (8.8 g/cm³), sterling silver 925 (10.4 g/cm³), 9k gold (11.2 g/cm³), 14k gold (13.1 g/cm³), 18k yellow gold (15.5 g/cm³). It is the same code as Design Facts in the Jart studio and the metal weight calculator, so the three never disagree. One pennyweight is 1.5552 g.

A mesh with holes encloses no definite volume, so the page shows no weight for it rather than a guess. Densities are typical values; a particular alloy can differ by a few percent.

What does the cast check look at?

Closed metal: every edge must join exactly two faces, or the printer and the caster get an open shell. Wall thickness: measured at every vertex by a ray through the metal; the minimums are 0.8 mm for silver and bronze and 0.6 mm for gold, common rules of thumb. Prongs around stones of 3 mm and up, and stone seats, when the model has stones. Each line says pass, check or fail with the number, and Wall thickness paints the thin areas red on the model.

Estimates from the 3D file's render mesh, measured by casting rays through it at each vertex: a guide for you and your caster, not a guarantee. Detail finer than the mesh is not seen. The minimums are common rules of thumb; ask your caster for theirs.

Can I cast a model made with an AI 3D tool?

Often, after a few fixes. Models from AI 3D tools usually have no real size, so check the size line and type the piece's real largest side (a ring is about 20 to 24 mm across). They are often open meshes or carry walls thinner than metal can fill: the cast check shows both, and the heat map shows where. A model with no part named as a stone is weighed as all metal.

Where does the metal price come from?

Jart has no live price feed, so the default is dated: the alloy's gold or silver content at the spot price on 10 Nov 2026 (gold US$4,075.20 and silver US$51.35 a troy ounce; 18k is 0.750 fine, 14k 0.585, 9k 0.375, sterling 0.925). Bronze is priced as casting grain bought retail that month. Prices move every day, so type today's price, or your caster's price per gram, in the price field. Costs are in US dollars, and what you type stays in this tab.

In the Jart studio (Pro and up, and early access accounts), share a design for approval; once it is approved, make a caster link for that exact version. Your caster sees the piece, its fingerprint and the estimated weight, marks it received and records the real cast weight. From three casts, Jart shows how far that caster's real weights run from the estimate, so your next estimate starts closer. Sign up free to try it.

Private by design

Nothing is uploaded. The page reads your file with the browser's file access, measures it on your own computer in a background worker so the tab stays responsive, and makes the caster pack there too. Our server sees only that this page was loaded.

Weigh a plain band from its size with the metal weight calculator, look up hallmarks and densities on the metals page, or turn a Rhino file into an STL with the 3DM to STL converter.

More free tools

No account, nothing to install. The help centre explains the studio itself.

See it rendered before it is cast.

Open the model in Jart, choose the metal and the stones, and render a photoreal image on your own graphics card. No account needed.

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